There are many art or craft implements employing needles for such purposes as embroidering and making hooked rugs, among others, which may require a loop of yarn or other material on one side of a fabric backing, for example. Such tools typically have a needle with an eye closely adjacent the pointed end. Such instruments normally having a handle which is comfortable for the user's hand have been made in different lengths but each needle and handle combination has typically had a fixed length relationship.
It has been found to be desirable to have such an implement with a needle having an adjustable length with respect to the handle for different length of loops or for other purposes. Examples of such a device are shown in U.S. Pat. Nos. 4,306,510 and 4,479,445. These devices have different structures but both of them have the purpose of providing an adjustable length needle in a craft implement. The first patent has a plastic handle with a cylindrical axial opening adapted to receive a unitary needle element having a threaded end and a pointed end. A threaded nut rotatable with respect to the handle is employed to adjust the length of the needle so that it projects outwardly from the handle by differing amounts. A pin and slot arrangement prevent rotation of the needle in the handle. U.S. Pat. No. 4,479,445 also provides a plastic handle with a needle element comprising a unitary needle and holder which are rotatably secured within the handle. This device rotates the entire needle element within the handle for accomplishing longitudinal adjustments. A projection inside the handle slidingly engages the threads on the holder to cause the relative longitudinal motion. This second patent is particularly adapted to incorporate a cannulation needle used in hypodermic syringes and is a simple adapter for use of such readily available needles.
A disadvantage of some of the prior art devices is that the needle and the adjusting threads are formed on a unitary member. Thus if the needle is changed, the threaded portion must also be changed. Alternatively the whole unit is disposable. Additionally, some of the prior art devices do not have means for retracting the needle point fully within the handle, thereby creating a safety hazard. Furthermore, U.S. Pat. No. 4,306,510 requires an additional element attached to the needle and an open slot in the handle portion to prevent rotation. This requires additional elements and the possibility of fouling the upper portion of the needle and the threads because they are exposed to the external environment and accompanying contamination through the slot in the side of the handle.